Questions tagged [hvac]

(Heating, Ventilating, and Air Conditioning) For questions about installing, repairing, and troubleshooting HVAC systems.

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37 views

Goodman HVAC - What are the outlets for?

My MIL has a Goodman HVAC installed and it's not cooling properly. I'm trying to understand what the outlets are for. One of them, is hooked into some PVC pipe which goes outside. The other outlet is ...
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Installing a relay to control duct fans!

I want to install a 24v/110 relay to control the two duct fans that I installed in my ducts. The idea is that the fans will come on when the blower comes on. To test this, I ran an 18/2 thermostat ...
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AC Replacement Proposal

Can someone please help to review if the following AC replacement proposal makes sense and sounds reasonable? Installation Remove and disposal of existing equipment, disassemble systems so they can be ...
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Should I add air ducts when finishing my basement or rely on space heaters?

I am going have a finished basement of 1000 sq/ft which includes a theater room of 12X16. Currently I am in process of planning in stalling duct work to my basement. I am thinking of not putting duct ...
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Can I have independent heating zones with a standard boiler?

We have a new standard gas boiler in our home along with two thermostats, one for the basement and one for the rest of the house (living room, bedrooms, etc). The problem we're having is that the ...
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1answer
51 views

How to properly use a transformer which bundles its high & low voltage wires together?

Here's an example of an HVAC transformer that will go from 120 or 240 to 24 VAC. Obviously, all wires exit the device through the same pipe nipple; the device is intended to be installed by screwing ...
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1answer
34 views

Why does adding refrigerant increase subcooling and decrease superheat?

Please correct my following notion of why adding refrigerant increases subcooling and decreases superheat: Let's assume a hypothetical situation: condensation point of uncompressed refrigerant (vapor ...
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Central Air condensate is pumped into a hole in the basement floor?

I’ve tried to do some research on this topic but am a little confused and would like to know if I’ve got a problem here that I need to remedy. I think I want to install a self-draining dehumidifier in ...
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1answer
61 views

AC “Dirty Sock Syndrome” smell went away, is it actually fine?

My AC has started to turn on with the warm weather and with that I've been smelling a gross musty sour smell coming from the vents (only when it cools and not when heater is on). I last changed the ...
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32 views

Extending a forced air heat register

Adding a small room. Want to extend HVAC to the new room. HVAC guy warned me very expensive for such a small job and told me (wink wink nudge nudge) easy to do it myself. Attic above: Question: The ...
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1answer
27 views

What could cause a central A/C system to smell but only after central heating had been used?

We have a central heating and air conditioning system in a single family home (in Southern California), where there is a large intake vent in the house that goes directly to the central house fan and ...
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1answer
46 views

Can I move air return higher?

I need to install some open shelving but the brackets they use are at a height that would interfere with the air return pictured. Would it be okay to relocate the return 4” higher or is there a reason ...
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What was this doing on my return air vent and why did it prevent installation of a filter?

We purchased a new home a little over three months ago. It had a rooftop AC unit installed in probably the late 90s/early 2000s. We were unable to have this tested during our inspection because the ...
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Can I safely cut a copper compressor pipe with r600a gas?

Can I safely cut a fridge compressors copper pipes if it uses r600a gas. I've read of people taking out fridge compressors but I want to check whether it's safe to cut the pipes like this?
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Does open stairs between basement and main living cost extra electricity bill?

Does with No door or open stairs between basement and main living lead extra electricity bill, specially in winter, even though entire basement is finished and well insulated ? We want to have open ...
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Inline Booster Fans

I have installed two inline duct booster fans to increase the airflow for my furnace/ac in a new addition that I got built. The new run that I installed is an 8" flex duct that runs about 25 ft. ...
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692 views

What should I replace this broken condensate line connection with?

This is on the condensation hose coming off of a 3" PVC pipe which I think is an exhaust for my HVAC system. The tube runs to a little electric pump on the floor that sends any collected water to ...
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46 views

Are shoe taps used on residential duct systems?

I've seen a variety of different style take-offs (Bell end, Conical, HETO etc) used on rectangular duct that are supposed to help transition the airflow. When it comes to round duct the closest thing ...
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issue with closed loop hot water heating

So I have an 1880s Victorian in Boston that is proving to be quite the adventure. I'm new to this, so hopefully I am using the right words. I have a four zone hot water heating system with radiators ...
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1answer
30 views

How do i reduce and split hvac duct from 8" round into two rooms

Hi i have small minisplit with 350 cf/m i attached a plenum with 8 inch ridgit round duct attached to it now i need to run it into a bulkhead where one register goes into a small room aprox 12x12 ...
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1answer
55 views

I accidentally short the c wire and both units not turning back on

I was trying to installed my nest thermostats.the power were shut off but it seem some current still in, so it short the system my question I can't located the fuse on the board so is that mean the ...
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Fan running 24 x7 despite Thermostat set to Auto for Fan

I have moved into a new condo unit in Toronto and it seems my fancoil keeps running 24x7 despite the thermostat set to Auto for Fan. Even when the temperature is set to a temperature lower than the ...
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If I have a Zoned HVAC system, should there be more than one filter to change?

In a house now for 6 months, just learned today I should have changed my filter twice already, whoops. I have a zoned system - two furnaces, one in the finished attic on its side, one in the basement. ...
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39 views

Can I vent my bathroom with Air Return Grilles?

My apartment’s small full bathroom is about 50 sq ft, and there was an old Non-Vented Air Recirculating Fan in the ceiling. It died but there was still moisture/mold/mildew issues when it worked. I ...
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1answer
24 views

HVAC running loud

I live in an apartment building with in-unit HVAC system. During the operations, when the fan is on, it is very loud. Is that normal (my neighbors' is whisper quite)? Is there something I can do, or ...
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3answers
407 views

How would I go about fitting a window AC into a really wide window?

I live in an apartment and have a central air system but my main bedroom always stays about 10-15 degrees hotter than the rest of the apartment. I reached out to my landlord about this problem and she ...
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1answer
37 views

In what situation is a slant top register boot the preferred choice?

I see them sold all over the place but when I search for information on them it is almost like they don't exist. In what situation does it make sense to choose that style of register boot?
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1answer
57 views

Enclosing utility room (furnace / water heater) basement

I have a very old furnace (HVAC) in a utility room (basement) with slatted door that’s very loud and was wondering if I could enclose the utility room (with mineral wool and solid doors) by adding ...
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41 views

Brand new Fujitsu Halcyon split system unable to keep temperature

We had a Fujitsu split system installed, with 4 indoor units. The issue I'm seeing is that the system is behaving in a way that I can only describe as "erratic". We're observing a couple of ...
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1answer
35 views

How are vapor barriers, moisture barriers, and house wrap different?

I've read many discussions here and elsewhere talking about these three things with regard to insulation, energy efficiency, and siding installation. What are the differences and where are each used?
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41 views

How do you wire a current sensor to multiple fans?

I have two booster fans that I only want to run when the main HVAC blower fan is on. Each fan will have its own speed controller. How do I wire them both to the same current sensor switch? Should I ...
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1answer
51 views

Roof truss with Odd 2x4 T-Shaped Reinforcement. Why is that there?

We needed to replace the air conditioning evaporator coil and air handling element. In this house the cooling element is located inside the attic of the house. And up in the attic space is really ...
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2answers
32 views

What type of register and/or installation method to use for a inside duct mounting holes?

I removed the original register cover from my vent, the screw mounts were inside the duct. I'm not sure if the fact that this is on an external wall has anything to do with it, but there was no bite ...
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37 views

Heater warms up but won't blow, fan is good

I have a Lennox Whisper Heat Central Heat unit model G20Q3E-75-4 natural gas heater. It worked fine until today, and nothing has changed about the house or the heater, we have electricity and gas. The ...
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1answer
39 views

How To Wire Humidistat and Humidifier - Honeywell

I am looking for advice on how to wire my new humidistat with my furance and humidifier. First, here are the components I'm working with: Furnace: Carrier WeatherMaker Infinity (Model 58MVP100 14120) ...
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Opportunity to relocated HVAC system from attic to basement

Our >10-year old HVAC system (heat pump and 3-ton air handler) need to be replaced. The heat pump is need of new parts, but we were advised given the age of the entire system that it would be more ...
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2answers
61 views

What goes into replacing a package unit (HVAC)?

I have an A/C, Heater package unit on the roof of my condo in Southern California. My unit works but my neighbor's unit just kicked the bucket and it is being replaced. The estimates she got varied ...
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34 views

HVAC furnance runs for awhile, stops for 2 minutes, then starts back up and continues to heat until set point reached

I have a Carrier 58GS150 system. At night it is set to 69. In the morning it is set to 72. Recently, I replaced the air filter. The system starts up fine in the morning and tries to reach 72. ...
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53 views

C Wire - Williamson Furnace/Honeywell Thermostat

I'm trying to install a new wifi thermostat, but am a little confused. I have 5 wires, but none are connected to the C in the thermostat, as seen below: Additionally, when I trace the thermostat to ...
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1answer
64 views

Wiring an ECM to AC power

I'm trying to wire a motor to work on 120v ac power. I accidentally bought an EC motor, because the price was so low, and cant find any sort of wire diagram for it From research, I found that all of ...
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c wire question

I have a gas fired hot water boiler with 18/2 thermostat wire running up to my regular non wifi thermostat . I want to know if I ran a single (blue ) 18 g wire from my c terminal on my new wifi ...
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40 views

Need to move my vertical HVAC return approx 3 inches away from my furnace

I installed a power humidifier to my furnace side (had to be mounted facing the face of the A-coil on the plenum per OEM) . and it's mounted in between my furnace and cold air return. The unit (...
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24 views

HVAC auxiliary fan relay wiring help

I set up a two zone whole house dehumidifier system with 24v no/nc dampers, primary and secondary zones. the primary zone is controlled by a Aprilaire model 76 external control and the secondary zone ...
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3answers
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Why would an air conditioning unit specify a maximum breaker size?

A ductless mini split unit I am interested in specifies a maximum breaker size of 15 amps. Why would this be the case? The unit is going to be installed on the opposite side of the house from where ...
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1answer
34 views

heat is not responding to thermostat set temp but comes on when turned off and back on with the thermostat switch

At times during the day my gas burner doesn't try to come back up to the set temperature on the upstairs or downstairs main thermostat. I'll hit the up button a couple of degrees but no change. Then ...
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1answer
34 views

Can I get away with 12" round supply and return for 2 ton?

replacing two package AC heat pumps that are 20+ years old, going to convert it to a split system with an air handler inside an insulated closet style box on the outside of the house. Ducts are in ...
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1answer
42 views

Can I use a 220v 60 amp breaker and 4/3 line for a sub panely with 2 breakers 220 1 35 amp and 1 15 amp

I have two old package heatpumps supplied by what looks like 4/3 lines each on its own breaker. 60 amp fuses. I am installing two split units the condenser requires 220 and 20 or 35 amp depending ...
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1answer
15 views

Two Sets of Wires on HVAC Panel

Ultimately I'm looking to use a C wire for a Nest thermostat, but upon looking at the HVAC panel I'm confused by the wiring. There's a grouping of wires going from the HVAC panel to the thermostat: ...
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2answers
37 views

24vac transformer inside furnace

I'm adding a humidifier to my furnace. The included 24vac transformer fits nicely on the inner electrical box in the upper furnace compartment. I like that it keeps everything behind the external ...
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Hard to Pin-Point High Temp Limit Switch Issue

I have been having an issue with my furnace for awhile now which can't seem to be solved. Had a furnace service out to review it and he spent 6 hours here trying everything. Below are the facts. ...

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